4.7 Comparing ionic and covalent compounds

Question 1

Metals and non-metals react to form ….

Answer 1

Ionic compounds

Question 2

Non-metals react to form ….

Answer 2

Covalent compounds

Question 3

The covalent compounds exist as ….

Answer 3

Molecules

Question 4

Particles in an ionic compound

Answer 4

are ions

Question 5

Particles in a covalent compound

Answer 5

are molecules.

Question 6

Charge in ionic solids.

Answer 6

In ionic solids, the particles are charged and the forces between them are strong.

Question 7

Charge in covalent solids.

Answer 7

In molecular covalent solids, the particles are not charged, and the forces between them are very weak.

Question 8

What does a regular arrangement of particles in a lattice always lead to?

Answer 8

Crystals

Question 9

Properties of ionic compounds

Answer 9

1. Ionic comopounds have high melting and boiling points.
2. Ionic compounds are usually soluble in water.
3. Ionic compounds conduct electricity, when melted or dissolved in water.

Question 10

Properties of covalent compounds

Answer 10

1. Molecular covalent compounds have low melting and boiling points.
2. Covalent compounds tend to be insoluble in water.
3. Covalent compounds do not conduct electricity.

Question 11

Why do ionic compounds have high melting and boiling points?

Answer 11

This is because the ionic bonds are very strong. It takes a lot of heat energy to break up the lattice. So ionic compounds are solids at room temperature.

Question 12

Why are ionic compounds usually soluble in water?

Answer 12

Ionic compounds are usually soluble in water because the water is able to separate the ions from each other. The ions then move apart, surrounded by water molecules.

Question 13

Why do ionic compounds conduct electricity, when melted or dissolved in water?

Answer 13

A solid ionic compound will not conduct electricity. But when it melts, or dissolves in water, the ions are free to move. Since they are charged they can then conduct electricity.

Question 14

Why do molecular covalent compounds have low melting and boiling points?

Answer 14

This is because the attraction between the molecules is low. So it does not take much energy to break up the lattice and separate them from each other. That explains why many molecular compounds are liquids or gases at room temperature and why many of the liquids are volatile.

Question 15

Volatile

Answer 15

Evaporate easily

Question 16

What are covalent compounds soluble in?

Answer 16

Covalent compounds dissolve in some solvents like tetrachloromethane.

Question 17

Why don’t covalent compounds conduct electricity?

Answer 17

There are no charged particles, so they cannot conduct.